that is the spot where the second bomb went off. former atf bombinvestigatorjimcavanaughsaid it is obvious to him looking at the pictures. >> large injuries were on the side of it. debris field to the left. some protected areas over on the right side that indicate the blast was to one side of the trash receptacle. this was the scene of the blast. >> reporter: we are also seeing close-up photos of the actual pieces of the bomb. showing the pressure cooker deformed by the blast, one of its lids blown to the top of a nearby building. they are a favorite of bomb makers because explosive pressure builds up before it is released. investigators can now begin to trace down where components were bought since they know the maker of the pressure cooker, the type of rechargeable flashlight batteries used -- made in china, but widely available -- and even the type of wire -- also made in china -- used to hook the main components together. bomb technicians are examining two electronic components included in the bombs to see whether they were parts of timers or receivers for a remote detonation signal. a